Jack Thorne, the prolific British writer behind HBO and BBC drama “His Dark Materials,” has said that he is receiving treatment for what he believes to be coronavirus.

The writer, whose other credits include Channel 4’s The Virtues and feature film The Aeronauts, said he has suffered from a high temperature, cough and exhaustion, which has aggravated his asthma. Thorne has been given a course of steroids and said his health is improving, but he remains out of sorts.

“Seem to have Covid, which is not reacting great with my asthma. Amazing treatment from my GP over the phone, taking the time to give me all sorts of tests THEN consulting with a colleague before prescribing. Feel like I’ve been run over by an elephant but in total awe of the NHS,” he tweeted on Monday.

In an update today, Thorne said: “Feeling better after two days of steroids. Still v tired, but the elephants has been replaced by a mountain lion. Of course it could not be Covid (wish we had Germany’s resources) in which case this is not reassuring to anyone. But, for me, at this moment, the drugs have worked.”

Thorne has not been tested because the UK’s testing regime is not as sophisticated as other countries, including Germany and South Korea, but said his doctor has been “amazing” throughout the process. His asthma means he is considered an “increased risk” individual by the health service. Thorne also suffers from a condition called cholinergic urticaria, which means he is allergic to heat and his own body movement. He calls it an “invisible disability.”

The writer has received hundreds of well-wishes on Twitter. “Sorry to hear this, Jack. Wishing you a rapid recovery,” said Bodyguard writer Jed Mercurio. Channel 4 CEO Alex Mahon added: “Look after yourself and rest.” Good Omens scribe Neil Gaiman also commented: “Sending love and worried get well wishes by the bucketload.”

Thorne, who penned the Harry Potter And The Cursed Child play, has written Damien Chazelle’s Netflix music drama The Eddy, the feature film Radioactive, starring Rosamund Pike as Marie Curie for Amazon and Studiocanal, and the Marc Munden-directed adaptation of The Secret Garden. He is currently adapting Charles Dickens’ classic novel A Tale of Two Cities with Legendary Global.